# Update A
## config.ext
foo = false
## src.py
from config import config
if config('foo'):
work(2 / 0)
else:
work(10 / 5)
# Update B
## config.ext
foo = true
The most insidious part of this is when there are entire swaths of infrastructure in place that circumvent the usual code review process in order to execute those configuration changes. Boolean flags like your `config('foo')` here are most common, but I've also seen nested dictionaries shoved through this way.